Forced air drying system for a dishwasher



Aug. 20, 1968 R. s. BRADEN 3,397,708

FORCED AIR DRYING SYSTEM FOR A DISHWASHER Filed Feb. 1, 1966 5Sheets-Sheet 1 INVENTOR.

7Z9 v /50/ 0); 6: Braden A)! ATTORNEY Aug. 20, 1968 R. s. BRADEN FORCEDAIR DRYING SYSTEM FOR A DISHWASHER 5 Sheets-Sheet 2 Filed Feb. 1. 1966Rm 3 M WM M %M w n R Aug. 20, 1968 R. s. BRADEN FORCED AIR DRYING SYSTEMFOR A DISHWASHER 5 Sheets-Sheet 5 Filed Feb. 1, 1966 INVENTOR. Ralph S:Braden BY A! ATTORNEY Aug. 20, 1968 R. s. BRADEN FORCED AIR DRYINGSYSTEM FOR A DISHWASHER 5 SheetsSheet 4 Filed Feb. 1, 1966 m in 3 M mr oMEX w 5% W H 5% z .7, l@\

Au 20, 1968 R. s. BRADEN 3,397,708

FORCEDAIR DRYING SYSTEM FOR A DISHWASHER Filed Feb. 1, 1966 5Sheets-Sheet 5 CONTACT TIME IN MINUTES OONTAC T CLOSED 8 CONTACT OPEN ORCLOSED INVENTOR.

50 2,0): 61 Braden Z9 7 I I O H26 ATYOR/VE Y United States PatentABSTRACT OF THE DISCLOSURE A domestic dishwashing chamber provided witha blower and a temperature responsive means outside the chamber to sensethe temperature of the chamber so as to initiate drying air circulationthrough the chamber after a predetermined temperature has been obtained.

This is a continuation-in-part of my application Ser. No. 350,991 filedMar. 11, 1964, now Patent No. 3,241,563.

This invention relates to a domestic appliance and more particularly toan improved apparatus for drying in a dishwasher using the cooling airof the pump motor for the dishwasher.

Automatic dishwashers are generally provided with a drying cyclefollowing the period during which the dishes are washed and rinsed. Thisdrying cycle is generally accomplished by heating the dishes tosterilize them and to vaporize the moisture droplets therefrom. Theprior art has also used a current of air through the dishwashingchamber, heated or otherwise, as an aid in drying the dishes during thedrying period. This invention is directed to an improved forced airsystem for drying dishes or the like in an automatic dishwasher.

Accordingly, it is a general object of this invention to provide aforced air drying system for a dishwasher.

It is another object of this invention to provide in a dishwasher aforced air drying system which utilizes the cooling air from adishwasher motor, thereby to economize on the heat necessary to performthe drying operation.

It is also an object of this invention to provide a forced air systemfor an automatic dishwasher which is adapted to exhaust to atmospherethe motor cooling air during the wash and rinse portions of an automaticdishwashing cycle and then to divert the motor cooling air through thedishwashing chamber during the drying portion of the automatic cycle,thereby to dry the dishes with heat from the motor.

A further object of this invention is the provision for such a forcedair drying system of an air flow diverter means which is responsive tothe dishwasher timer to divert air flow from the atmosphere to thedishwashing chamber at a predetermined time in said automatic cycle.

A still further object of this invention is the provision for such aforced air drying system of an air flow diverter means which isthermally responsive to temperatures in the dishwashing chamber, therebyto initiate the flow of forced air through the dishwashing chamber afterthe dishes have been elevated to a sanitizing temperature by anauxiliary heater.

Another object of this invention is the provision of an optional forcedair drying system for a dishwasher and more particularly to such asystem in which an auxiliary blower means is adapted for subsequentattachment to the outside of a dishwasher .tub wherein said blower meansincludes means operably responsive to the temperature of the tub forstarting a drying air flow when the temperature of the tub reaches apredetermined value.

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Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a front elevational view, with parts broken away, of adishwasher suitable for use with this invention and provided with oneembodiment thereof;

FIGURE 2 is a fragmentary sectional view, partly in elevation, takenalong line 22 in FIGURE 1;

FIGURE 3 is a fragmentary sectional view, partly in elevation, takenalong line 3-3 in FIGURE 2;

FIGURE 4 is a fragmentary side elevational view similar to FIGURE 1showing another embodiment of this invention.

FIGURE 5 is a fragmentary sectional view, partly in elevation of stillanother embodiment of this invention;

FIGURE 6 is a fragmentary sectional view, partly in elevation, takenalong line 66 in FIGURE 5;

FIGURE 7 is a schematic wiring diagram suitable for use with theembodiment of FIGURE 5; and

FIGURE 8 is a timer cycle chart showing the operation of the schematicwiring diagram of FIGURE 7.

In accordance with this invention and with reference to FIGURE 1, adishwasher 10 is illustrated. The dishwasher 10 is comprised of a casing12 which defines a dishwashing chamber 14 having a front opening. Thebottom of the dishwashing chamber 14 is closed by a bulkhead or bottomwall 18 which has a depressed sump area 20 in a central portion thereof.The sump leads to a pump 22 which is operated by an electric motor 24.Within the dishwashing chamber 14, a rotatably mounted spray tube 26 ispositioned and interconnected with the pump 22 by way of a conduit 28.Interposed in the fluid stream between the spray tube and the pump is adiverter valve 30 which may be selectively energized to direct theoutput of the pump either to the spray tube 26 or to a drain line 32.Water may be admitted to the sump 20 by means of a Water valve 34, andan electric heater 36 is included in the sump for sanitizing the dishesat the conclusion of a dishwashing cycle and for aiding in the drying ofthe dishes in accordance with the teachings of this invention to be setforth more fully hereinafter. The heater 36 is also used to maintain thetemperature of the water throughout the dishwashing cycle.

The front opening of the dishwashing chamber is closed by a door 38which is hingedly mounted at 40 so that the door may be placed in avertical position as shown for closing the dishwashing chamber and in ahorizontally disposed position for loading the dishwashera dishsupporting rack 39 being slidably removable on the door in its openposition for this purpose. A conventional timer 42 is included in thedoor for selectively and sequentially operating the water valve 34, thepump motor 24, the heater 36 and the diverter valve 30 in a conventionaldishwashing cycle. For additional details pertaining in particular tothe dishwasher construction and control cycle therefor, reference may behad to the patent to Abresch et al., 2,734,520, issued Feb. 14, 1956.

A conventional dishwashing cycle, such as taught in Abresch et al, mayinclude the sequential periods of FLUSHING out the interior of thedishwashing chamber 14, while the diverter valve 30 is conditioned todirect the water to drain; a FHL period during which time the valve 34supplies wash water to the chamber 14 with the diverter valve 30conditioned to direct water from the pump 22 to the spray tube 26; aWASH period during which time the water is recirculated between the sumpand the spray tube by the pump 22; a DRAIN period during which time thediverter valve 30 is conditioned to direct the water from the sump tothe drain 32 with the pump 22 operating; a second FILL period; a RINSEperiod during which the second fill is circulated to rinse the soiledwash water from the surface of the dishes; a second FLUSHING periodfollowed by a third FILL period and a third RINSE period and a finalDRAIN period. The foregoing cycle operations precede the DRY- ING cycleduring which time the moisture droplets deposited on the dishes duringthe final rinse are vaporized from the surface thereof.

In a dishwasher constructed in accordance with this invention the rateat which the dishes are dried can be increased by introducing air,forced first through the motor for cooling thereof, and then into thedishwashing chamber during all or some portion of the drying cycle. Inthis manner the heat of the motor is added either exclusively to thedrying chamber or in addition to the heat output of the heater 36 whichmay or may not be energized.

In accordance With the concept of this invention and turning now toFIGURE 1, the dish drying system is shown comprised of a blower housingassembly 50 and a heat duct assembly 52, both of plastic such asMonsanto Corporations 410 (ABS). In general, the duct work 50, 52conveys the cooling air from the motor 24 to the dishwashing chamber 14.

More specifically, the blower housing assembly 50 is comprised of anupper shroud 54 and a lower shroud 56 which snugly circumscribe theouter casing of the motor 24-the shrouds being spaced from the motorcasing to form a duct 58 adjacent the motor cooling ports 60 in themotor jacket. A flexible conduit 66 interconnects one end 68 of theblower housing assembly with the inlet end 70 to the heat duct assembly52 to minimize transmission of motor noise.

The heat duct assembly 52 is comprised of an upstanding duct 72 whichcommunicates with the dishwashing chamber 14 through an opening 74 inthe sidewall thereof-an inverted cup-like deflector 76 serving toprevent spray from entering the duct work. With reference to FIGURE 3,an opening 80 is provided in the lower end of the duct for selectivelyexhausting the cooling air of the motor into the machinery compartment21 of the dishwasher and from there to atmosphere. A diverter valve orflapper 82 is pivoted at 84 between the solid line position A (FIGURE 3)wherein the air is channeled from the motor to the dishwashing chamberand a phantom line position B wherein the motor cooling air is exhaustedinto the machinery compartment.

Forced air currents are provided to the dishwashing chamber by the motor24 which includes a casing having inlets 86 on the top and bottom of itscasing as well as the outlet ports 60 around the side thereof. Inaccordance with conventional practice, an impeller 90 is rotatablymounted within the motor casing for rotation with the motor rotor,thereby to induce currents through the motor via the inlets 86 and theoutlets 60 into the blower housing 50. Heat is entrained from the motorcomponents in passing therethrough and this heat is added to thedishwashing chamber 14 whenever the flapper valve 82 is in its Aposition. Air entering the dishwashing chamber 14 through the deflector76 exhausts from the dishwashing chamber by means of vents 94, 96extending through the door 38 of the dishwasher.

In one embodiment the damper 82 may be moved between the positions A andB by means of a solenoid 98 which is selectively energized by the timer42 at the start of the drying cycle or at some time shortly thereafter.

In another embodiment and with reference to FIGURE 4, the damper 82 maybe moved in response to the temperature within the dishwashing chamber14 by means of a temperature responsive device 100 which actuates aswitch 102 in series with the solenoid 98. In this arrangement it ispossible to allow time for the temperatures within the dishwashingchamber to increase sufiiciently to sanitize the dishes before the motoris energized and the cooling air thereof is diverted through the dish- 4washing chamber to carry away the vapors from the drying operation andto dry the dishes.

In line with making the forced air drying system responsive to thetemperature in the dishwashing chamber, my invention also facilitatesthe incorporation of such a drying system as an optional extra which maybe added to an earlier purchased dishwasher without forced air drying.It is thus an object of my invention to provide a forced air dryingarrangement which is responsive to dishwasher temperature rather thanthe dishwasher timer so that subsequent installation is comparativelyquick and simple.

With reference to FIGURES 5 and 6, a blower means is adapted forattachment to a casing means or tub wall 112 which defines thedishwashing chamber of an appliance such as shown in FIGURE 1 or astaught in copending application Ser. No. 403,479 filed Oct. 13, 1964,now Patent No. 3,292,645, and having the same assignee as thisapplication.

More particularly, the blower means 110 attaches to the outside of thetub wall adjacent an opening 174 in the tub wall and in communicationtherethrough with the interior of the dishwashing chamber 114. It shouldbe understood that air entering the chamber 114 through the opening 174will leave the chamber through suitable vent openings such as 94, 96 inFIGURE 1, the arrangement of the inlet opening 174 with regard to thevent openings being such as to provide a good coverage of the interiorof the chamber 114 so as to completely sweep the steamy vapor from thechamber during the drying portion of the wash cycle. Although FIGURE 1shows the inlet on the side and the vents on the door to simplify thedrawing, in reality, the air sweep of the chamber would be improved withthe inlet 174 on the back wall of the tub as shown in the aforementionedcopending case.

The blower means is comprised of a sheet metal support wall 118 and anopen-sided plastic duct 120 closed by the support wall and held theretoby bent-over tangs 122 which grip aperipheral flange 124 on the plasticduct member 120. A fan housing 126 is formed at the lower end of theduct member which has an inlet opening 128 con nected to the atmosphereand an outlet 130 connected to a duct 132 formed by the upper portion ofthe duct member 120.

Any suitable fastening arrangement may be used to attach the blowermeans 110 to the tub, but a preferred arrangement places the tub wall112 in sandwiched relationship between the blower means on the outsideand a plastic vent cover 116 on the inside. Fastening means, such asscrews 115, extend through side flanges 117 on the vent cover from theinside of the chamber 114 into engagement with the casing wall 112. Theblower means 110 is attached to the outside of the casing wall 112 byscrews 133 extending into the support wall 118. Since the dishwasher isoriginally provided with the vent cover 116 to protect the vent opening174 from splash-out, attachment of the blower means is made simply byremoving the vent cover 116, aligning the blower means with the ventopening 174, inserting the screws 133 and replacing the vent cover 116.

At one side of support wall 118 (FIGURE 6) and attached thereto is anofiset bracket which carries a thermally responsive, high differential,disc type thermostat 142 which includes a thermally sensitive actuatorportion 144 in touching thermally responsive engagement with the outsideof the tub wall 112. The thermostat 142 is the sole control of theblower means 110 as will be explained more fully hereinafter.

An impeller 148 in the fan housing 126 is drivably connected to a shaft150 of an electric motor 152. A conductor 154 extends between thethermostat 142 and the motor 152 and serves to condition the motor 152for energization whenever the temperature of the air in the dishwashingchamber, as reflected by the temperature of tub wall 112, reaches apredetermined temperature such as 150 F.

Of particular importance is the fact that the blower means 110 isindependent from the timing control system of the dishwasher and thusmay be used as an optional addition to an earlier purchased dishwasherWithout forced air drying--a feature which is generally recognized asspeeding up the drying process. In operation the blower means acts as aslave to the heater 136 in the dishwashing chamber rather than to atimer such as 160 (FIGURE 7). In this regard the thermostat 142 ispositioned adjacent to the heater 136 so that radiations from theheater, when the heater is dry during the drying portions of the cycle,will also affect the operation of the thermostat in addition to thetemperature of the casing wall 112 which reflects the temperatureconditions of the chamber 114.

With reference to FIGURES 7 and 8 which depict the control system of adishwasher of the type taught in the aforementioned copendingapplication, the operation of this invention will now be set forth. Themeans 134 for supplying water until a pressure switch 135 opens toterminate fill, the means 124 for distributing this water to wash thedishes and then, by reversing, to drain the dirty water after the dishesare washed, and the means 136 for heating the water during washing andthen subsequently to provide heat in the chamber for drying these dishesare all under the control of a timer 160 which actuates timer switches162, 164 and 166 in accordance with a schedule shown in the timer cyclechart of FIGURE 8, wherein the listed contact members correspond toreference numbers 1, 2, 3, 4, 5 and 6 in FIGURE 7. In accordance withconventional practice, the control system of FIG- URE 7 may also includea door switch 170 to interrupt power from a 115-volt power supply L Lwhenever the access door to the dishwashing chamber is opened; and apush-pull switch 172 on one end of the axially shiftable timer shaftwhich is closed whenever the timer 160 is actuated to control adishwashing cycle.

The motor 124 includes a main run winding 180, a water distributingstart winding 182 and a water draining start winding 184-. A currentresponsive start relay 186 serves to energize the appropriate startwinding in accordance with the timer selection of contacts 5 or 6 for abrief period until the motor comes up to its designed running speed andcurrent flow in the main winding drops off.

In the context of FIGURE 7 it can now be seen that the blower means 110is independent of the timing means 160 and is, indeed, responsive to acondition in the dishwasher rather than to either a function or controlof the dishwasher. Power for the motor 152 of the forced air blower issupplied through conductors 188, 190 directly across the domestic powersupply L L and controlled solely by the thermostat 142 which, in turn,is controlled by and is responsive to the temperature of the dishwashingchamber. A differential of about 30 (152 F. on and 122 F. off) in thethermostat 142 has been found adequate to prevent premature lblowershut-down at the start of the forced air drying due to rapid temperaturedrop in the dishwashing chamber brought about by the initial airmovement.

The preferred foregoing attachment of the optional blower means couldactually be effected electrically by a separate wall plug at the end ofconductors 188 and 190. It should be appreciated, however, that theblower means could be connected in parallel with the heater 136 inseries with one or more of the timer switches so that power to theblower means could also be controlled through the timer.

While the embodiments of the present invention as herein disclosedconstitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In combination, casing means defining a. vented chamber for washingdishes or the like, means for supplying water to said chamber, means fordistributing the water supplied throughout said chamber and for drainingthe water from said chamber, means for heating in said chamber, timingmeans for controlling said water supply means, said distributing anddraining means and said heating means in a washing and drying cycle, andmeans outside of said chamber responsive to the temperature of saidcasing means and independent of said timing means for impelling a streamof drying air through said chamber, said means outside of said chamberincluding a blower means and a thermostat means in control relationshipwith said blower means for operating said blower means when thetemperature of said casing means reaches a predeter mined value.

2. The combination of claim 1 wherein said blower means and saidthermostat means are carried on a bracket means removably attachable tothe outside of said casing means.

3. The combination of claim 1 wherein said thermostat means is atemperature responsive switch in contact with the outside of said casingmeans adjacent said heating means.

4. For use with a dishwasher having casing means defining a ventedchamber for washing dishes or the like, means for supplying water tosaid chamber, means for distributing the water supplied throughout saidchamber, means for heating in said chamber and timing means forcontrolling said water supply means, said distributing means and saidheating means in a washing and drying cycle, optional forced air dryingmeans adapted to be fastened to said casing means in communication withsaid chamber and including a fan motor and means in control relationshipwith said fan motor and adapted for touching engagement with said casingmeans to be responsive to the temperature in said chamber for energizingsaid motor to impel a stream of drying air through said chamber, saidoptional forced air drying means being energizable independently of thetiming means of said dishwasher.

References Cited UNITED STATES PATENTS 1,687,458 10/1928 Lancelot et al134-57 3,125,105 3/1964 Geiger 134-58 3,241,563 3/1966 Braden 13457FOREIGN PATENTS 597,487 1/ 1948 Great Britain.

ROBERT L. BLEUTGE, Primary Examiner.

